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/*
 * Copyright (c) 2013, Stephen Colebourne & Michael Nascimento Santos
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  * Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 *  * Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 *  * Neither the name of JSR-310 nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package java.time.chrono;

import static java.time.temporal.ChronoField.MONTH_OF_YEAR;
import static java.time.temporal.ChronoUnit.DAYS;
import static java.time.temporal.ChronoUnit.MONTHS;
import static java.time.temporal.ChronoUnit.YEARS;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.ObjectStreamException;
import java.io.Serializable;
import java.time.DateTimeException;
import java.time.temporal.ChronoUnit;
import java.time.temporal.Temporal;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.TemporalAmount;
import java.time.temporal.TemporalQueries;
import java.time.temporal.TemporalUnit;
import java.time.temporal.UnsupportedTemporalTypeException;
import java.time.temporal.ValueRange;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Objects;

/**
 * A period expressed in terms of a standard year-month-day calendar system.
 * <p>
 * This class is used by applications seeking to handle dates in non-ISO calendar systems.
 * For example, the Japanese, Minguo, Thai Buddhist and others.
 *
 * @implSpec This class is immutable nad thread-safe.
 * @since 1.8
 */
final class ChronoPeriodImpl
    implements ChronoPeriod, Serializable {
  // this class is only used by JDK chronology implementations and makes assumptions based on that fact

  /**
   * Serialization version.
   */
  private static final long serialVersionUID = 57387258289L;

  /**
   * The set of supported units.
   */
  private static final List<TemporalUnit> SUPPORTED_UNITS =
      Collections.unmodifiableList(Arrays.<TemporalUnit>asList(YEARS, MONTHS, DAYS));

  /**
   * The chronology.
   */
  private final Chronology chrono;
  /**
   * The number of years.
   */
  final int years;
  /**
   * The number of months.
   */
  final int months;
  /**
   * The number of days.
   */
  final int days;

  /**
   * Creates an instance.
   */
  ChronoPeriodImpl(Chronology chrono, int years, int months, int days) {
    Objects.requireNonNull(chrono, "chrono");
    this.chrono = chrono;
    this.years = years;
    this.months = months;
    this.days = days;
  }

  //-----------------------------------------------------------------------
  @Override
  public long get(TemporalUnit unit) {
    if (unit == ChronoUnit.YEARS) {
      return years;
    } else if (unit == ChronoUnit.MONTHS) {
      return months;
    } else if (unit == ChronoUnit.DAYS) {
      return days;
    } else {
      throw new UnsupportedTemporalTypeException("Unsupported unit: " + unit);
    }
  }

  @Override
  public List<TemporalUnit> getUnits() {
    return ChronoPeriodImpl.SUPPORTED_UNITS;
  }

  @Override
  public Chronology getChronology() {
    return chrono;
  }

  //-----------------------------------------------------------------------
  @Override
  public boolean isZero() {
    return years == 0 && months == 0 && days == 0;
  }

  @Override
  public boolean isNegative() {
    return years < 0 || months < 0 || days < 0;
  }

  //-----------------------------------------------------------------------
  @Override
  public ChronoPeriod plus(TemporalAmount amountToAdd) {
    ChronoPeriodImpl amount = validateAmount(amountToAdd);
    return new ChronoPeriodImpl(
        chrono,
        Math.addExact(years, amount.years),
        Math.addExact(months, amount.months),
        Math.addExact(days, amount.days));
  }

  @Override
  public ChronoPeriod minus(TemporalAmount amountToSubtract) {
    ChronoPeriodImpl amount = validateAmount(amountToSubtract);
    return new ChronoPeriodImpl(
        chrono,
        Math.subtractExact(years, amount.years),
        Math.subtractExact(months, amount.months),
        Math.subtractExact(days, amount.days));
  }

  /**
   * Obtains an instance of {@code ChronoPeriodImpl} from a temporal amount.
   *
   * @param amount the temporal amount to convert, not null
   * @return the period, not null
   */
  private ChronoPeriodImpl validateAmount(TemporalAmount amount) {
    Objects.requireNonNull(amount, "amount");
    if (amount instanceof ChronoPeriodImpl == false) {
      throw new DateTimeException(
          "Unable to obtain ChronoPeriod from TemporalAmount: " + amount.getClass());
    }
    ChronoPeriodImpl period = (ChronoPeriodImpl) amount;
    if (chrono.equals(period.getChronology()) == false) {
      throw new ClassCastException(
          "Chronology mismatch, expected: " + chrono.getId() + ", actual: " + period.getChronology()
              .getId());
    }
    return period;
  }

  //-----------------------------------------------------------------------
  @Override
  public ChronoPeriod multipliedBy(int scalar) {
    if (this.isZero() || scalar == 1) {
      return this;
    }
    return new ChronoPeriodImpl(
        chrono,
        Math.multiplyExact(years, scalar),
        Math.multiplyExact(months, scalar),
        Math.multiplyExact(days, scalar));
  }

  //-----------------------------------------------------------------------
  @Override
  public ChronoPeriod normalized() {
    long monthRange = monthRange();
    if (monthRange > 0) {
      long totalMonths = years * monthRange + months;
      long splitYears = totalMonths / monthRange;
      int splitMonths = (int) (totalMonths % monthRange);  // no overflow
      if (splitYears == years && splitMonths == months) {
        return this;
      }
      return new ChronoPeriodImpl(chrono, Math.toIntExact(splitYears), splitMonths, days);

    }
    return this;
  }

  /**
   * Calculates the range of months.
   *
   * @return the month range, -1 if not fixed range
   */
  private long monthRange() {
    ValueRange startRange = chrono.range(MONTH_OF_YEAR);
    if (startRange.isFixed() && startRange.isIntValue()) {
      return startRange.getMaximum() - startRange.getMinimum() + 1;
    }
    return -1;
  }

  //-------------------------------------------------------------------------
  @Override
  public Temporal addTo(Temporal temporal) {
    validateChrono(temporal);
    if (months == 0) {
      if (years != 0) {
        temporal = temporal.plus(years, YEARS);
      }
    } else {
      long monthRange = monthRange();
      if (monthRange > 0) {
        temporal = temporal.plus(years * monthRange + months, MONTHS);
      } else {
        if (years != 0) {
          temporal = temporal.plus(years, YEARS);
        }
        temporal = temporal.plus(months, MONTHS);
      }
    }
    if (days != 0) {
      temporal = temporal.plus(days, DAYS);
    }
    return temporal;
  }


  @Override
  public Temporal subtractFrom(Temporal temporal) {
    validateChrono(temporal);
    if (months == 0) {
      if (years != 0) {
        temporal = temporal.minus(years, YEARS);
      }
    } else {
      long monthRange = monthRange();
      if (monthRange > 0) {
        temporal = temporal.minus(years * monthRange + months, MONTHS);
      } else {
        if (years != 0) {
          temporal = temporal.minus(years, YEARS);
        }
        temporal = temporal.minus(months, MONTHS);
      }
    }
    if (days != 0) {
      temporal = temporal.minus(days, DAYS);
    }
    return temporal;
  }

  /**
   * Validates that the temporal has the correct chronology.
   */
  private void validateChrono(TemporalAccessor temporal) {
    Objects.requireNonNull(temporal, "temporal");
    Chronology temporalChrono = temporal.query(TemporalQueries.chronology());
    if (temporalChrono != null && chrono.equals(temporalChrono) == false) {
      throw new DateTimeException(
          "Chronology mismatch, expected: " + chrono.getId() + ", actual: " + temporalChrono
              .getId());
    }
  }

  //-----------------------------------------------------------------------
  @Override
  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    }
    if (obj instanceof ChronoPeriodImpl) {
      ChronoPeriodImpl other = (ChronoPeriodImpl) obj;
      return years == other.years && months == other.months &&
          days == other.days && chrono.equals(other.chrono);
    }
    return false;
  }

  @Override
  public int hashCode() {
    return (years + Integer.rotateLeft(months, 8) + Integer.rotateLeft(days, 16)) ^ chrono
        .hashCode();
  }

  //-----------------------------------------------------------------------
  @Override
  public String toString() {
    if (isZero()) {
      return getChronology().toString() + " P0D";
    } else {
      StringBuilder buf = new StringBuilder();
      buf.append(getChronology().toString()).append(' ').append('P');
      if (years != 0) {
        buf.append(years).append('Y');
      }
      if (months != 0) {
        buf.append(months).append('M');
      }
      if (days != 0) {
        buf.append(days).append('D');
      }
      return buf.toString();
    }
  }

  //-----------------------------------------------------------------------

  /**
   * Writes the Chronology using a
   * <a href="../../../serialized-form.html#java.time.chrono.Ser">dedicated serialized form</a>.
   * <pre>
   *  out.writeByte(12);  // identifies this as a ChronoPeriodImpl
   *  out.writeUTF(getId());  // the chronology
   *  out.writeInt(years);
   *  out.writeInt(months);
   *  out.writeInt(days);
   * </pre>
   *
   * @return the instance of {@code Ser}, not null
   */
  protected Object writeReplace() {
    return new Ser(Ser.CHRONO_PERIOD_TYPE, this);
  }

  /**
   * Defend against malicious streams.
   *
   * @param s the stream to read
   * @throws InvalidObjectException always
   */
  private void readObject(ObjectInputStream s) throws ObjectStreamException {
    throw new InvalidObjectException("Deserialization via serialization delegate");
  }

  void writeExternal(DataOutput out) throws IOException {
    out.writeUTF(chrono.getId());
    out.writeInt(years);
    out.writeInt(months);
    out.writeInt(days);
  }

  static ChronoPeriodImpl readExternal(DataInput in) throws IOException {
    Chronology chrono = Chronology.of(in.readUTF());
    int years = in.readInt();
    int months = in.readInt();
    int days = in.readInt();
    return new ChronoPeriodImpl(chrono, years, months, days);
  }

}
